Add more output when roll scripts are retrying.

tools/push-to-trunk/common_includes.py

 #!/usr/bin/env python
 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
@@ skipping 300 matching lines @@
       wait_plan: A list of waiting delays between retries in seconds. The
                  maximum number of retries is len(wait_plan).
     """
     retry_on = retry_on or (lambda x: False)
     wait_plan = list(wait_plan or [])
     wait_plan.reverse()
     while True:
       got_exception = False
       try:
         result = cb()
-      except NoRetryException, e:
+      except NoRetryException as e:
         raise e
-      except Exception:
-        got_exception = True
+      except Exception as e:
+        got_exception = e
       if got_exception or retry_on(result):
         if not wait_plan:  # pragma: no cover
-          raise Exception("Retried too often. Giving up.")
+          raise Exception("Retried too often. Giving up. Reason: %s" %
+                          str(got_exception))
         wait_time = wait_plan.pop()
         print "Waiting for %f seconds." % wait_time
         self._side_effect_handler.Sleep(wait_time)
         print "Retrying..."
       else:
         return result
 
   def ReadLine(self, default=None):
     # Don't prompt in forced mode.
     if self._options.force_readline_defaults and default is not None:
@@ skipping 314 matching lines @@
     for (number, step_class) in enumerate(step_classes):
       steps.append(MakeStep(step_class, number, self._state, self._config,
                             options, self._side_effect_handler))
     for step in steps[options.step:]:
       if step.Run():
         return 1
     return 0
 
   def Run(self, args=None):
     return self.RunSteps(self._Steps(), args)